How to send current value of a property from ThingWorx to a web service on triggering of an alert(in the form of json)

Hi Priyanshi, you can try the following steps to achieve what you are looking for :

1. Create an alert on the property, if doesn't already exist
2. Create a service that outputs the data in the required data type e.g. Json which needs to be passed to the web service (see screenshot below) and for getting the current value of the property you can use the Stream and it's generic service GetStreamEntriesWithData or QueryStreamEntriesWithData (depending on your requirement)

     3. Create a subscription with Event -> Alert and select the Property on which the Alert will be fired and you would call this service created in above step (Step 2)

Hope this helps.